Imageable seamed belts having hot melt processable, thermosetting resin and conductive carbon filler adhesive between interlocking seaming members

ABSTRACT

A seamed flexible belt having a substrate, a seam having interlocking seam members, and an optional overcoat, wherein the interlocking seam members are held together by an adhesive having a resistive, hot-melt processible, thermosetting resin and carbon filler, for use in electrostatographic, contact electrostatic, digital and other like machines.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Attention is directed to U.S. patent application Ser. No.08/004,636 (D/97525) filed Jan. 8, 1998, entitled “Process and Apparatusfor Producing an Endless Seamed Belt;” U.S. patent application Ser. No.09/493,445 (D/97525D), filed Jan. 28, 2000, entitled “Process andApparatus for Producing an Endless Seamed Belt;” U.S. patent applicationSer. No. 09/470,931 (D/99689) filed Dec. 22, 1999 entitled “ContinuousProcess for Manufacturing Imageable Seamed Belts for Printers; “U.S.patent application Ser. No. 09/088,011, (D/97683), filed May 28, 1998,entitled, “Unsaturated Carbonate Adhesives for Component Seams;” U.S.patent application Ser. No. 09/615,444 (D/99598), filed Jul. 13, 2000,entitled, “Polyimide Adhesive For Polyimide Component InterlockingSeams;” U.S. patent application Ser. No. 09/615,426 (D/99598Q), filedJul. 13, 2000, entitled, “Process for Seaming Interlocking Seams OfPolyimide Component Using Polyimide Adhesive”; U.S. patent applicationSer. No. 09/660,248 (D/99610), filed Sep. 13, 2000, entitled, “ImageableSeamed Belts Having Fluoropolymer Adhesive Between Interlocking SeamingMembers;” U.S. patent application Ser. No. 09/660,249 (D/99610Q), filedSep. 13, 2000, entitled, “Imageable Seamed Belts Having FluoropolymerOvercoat;” U.S. patent application Ser. No. ______ (D/A0895Q), filed______, entitled “Conductive Carbon Filled Polyvinyl Butyral Adhesive;”U.S. patent application Ser. No. ______, (D/A0895Q1), filed ______,entitled, “Dual Curing Process for Producing a Puzzle Cut Seam;” U.S.patent application Ser. No. ______ (A0584), filed ______, entitled,“Imageable Seamed Belts Having Polyamide Adhesive Between InterlockingSeaming Members;” and U.S. patent application Ser. No. ______ (A0584Q),filed ______, entitled, “Polyamide and Conductive Filler Adhesive.” Thedisclosures of each of these references are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention is directed to transfer members useful inelectrostatographic, including digital apparatuses. In specificembodiments, the present invention is directed to seamed belts, and morespecifically, to endless flexible seamed belts wherein an image can betransferred at the seam of the belt with little or no print defectscaused by the seam. In embodiments, the present invention relates toxerographic component imageable seamed belts comprising an adhesiveformed between mutually mating elements of a seam, wherein the adhesivecomprises a polymer, preferably with an electrically conductive fillerdispersed or contained therein. In a particularly preferred embodiment,the polymer is selected from polyvinyl butyral, phenolic resins andmixtures thereof. Preferably, the filler is an electrically conductiveor semi-conductive carbon filler such as carbon black, fluorinatedcarbon, or mixtures thereof. The present invention further provides, inembodiments, a belt having a seam with increased strength because theadhesive is crosslinked. Preferably, the seam is strong enough tosurvive mechanical flexing while under tension, as the belt travels overvarious diameter rollers. The present invention, in embodiments, alsoprovides a belt having a seam in which the height differential betweenthe seam and the rest of the belt is virtually nil. The belt, inembodiments, allows for image transfer at the seam, which cannot beaccomplished with known seamed belts. Image transfer is accomplishedpartly because the present seam possesses the desired conductivity andrelease properties required for sufficient transfer. Image transfer isfurther made possible because the adhesive seam of the present inventionis virtually or completely free of bubbles, voids, and other inclusionswhich may impact high quality image transfer at the seam region.

[0003] In a typical electrostatographic reproducing apparatus such as anelectrophotographic imaging system using a photosensitive member, alight image of an original to be copied is recorded in the form of anelectrostatic latent image upon a photosensitive member and the latentimage is subsequently rendered visible by the application of a developermixture. One type of developer used in such printing machines is aliquid developer comprising a liquid carrier having toner particlesdispersed therein. Generally, the toner is made up of resin and asuitable colorant such as a dye or pigment. Conventional charge directorcompounds may also be present. The liquid developer material is broughtinto contact with the electrostatic latent image and the colored tonerparticles are deposited thereon in image configuration.

[0004] The developed toner image recorded on the imaging member istransferred to an image receiving substrate such as paper via a transfermember. The toner particles may be transferred by heat and/or pressureto a transfer member, or more commonly, the toner image particles may beelectrostatically transferred to the transfer member by means of anelectrical potential between the imaging member and the transfer member.After the toner has been transferred to the transfer member, it is thentransferred to the image receiving substrate, for example by contactingthe substrate with the toner image on the transfer member under heatand/or pressure.

[0005] Transfer members enable high throughput at modest process speeds.In four-color photocopier or printer systems, the transfer member alsoimproves registration of the final color toner image. In such systems,the four component colors of cyan, yellow, magenta and black may besynchronously developed onto one or more imaging members and transferredin registration onto a transfer member at a transfer station.

[0006] In electrostatographic printing and photocopy machines in whichthe toner image is transferred from the transfer member to the imagereceiving substrate, it is desired that the transfer of the tonerparticles from the transfer member to the image receiving substrate besubstantially 100 percent. Less than complete transfer to the imagereceiving substrate results in image degradation and low resolution.Complete transfer is particularly desirable when the imaging processinvolves generating full color images since undesirable colordeterioration in the final colors can occur when the color images arenot completely transferred from the transfer member.

[0007] Thus, it is desirable that the transfer member surface hasexcellent release characteristics with respect to the toner particles.Conventional materials known in the art for use as transfer membersoften possess the strength, conformability and electrical conductivitynecessary for use as transfer members, but can suffer from poor tonerrelease characteristics, especially with respect to higher gloss imagereceiving substrates.

[0008] Polyimide substrate transfer members are suitable for highperformance applications because of their outstanding mechanicalstrength and thermal stability, in addition to their good resistance toa wide range of chemicals. However, the high cost of manufacturingunseamed polyimide belts has led to the introduction of a seamed belt.

[0009] In the electrostatic transfer applications, use of a seamedtransfer polyimide member results in insufficient transfer in that thedeveloped image occurring on the seam is not adequately transferred.This incomplete transfer is partially the result of the difference inseam height to the rest of the belt. A “bump” is formed at the seam,thereby hindering transfer and mechanical performance. The developmentof puzzle cut seams has increased the quality of transfer somewhat, bydecreasing the seam height, thereby allowing smooth cycling. However,even with the improvements made with puzzle cut seams, quality imagingin the seamed area is not obtainable at present due, in part, tocontrast in transfer caused by differences in electrical and releaseproperties of known seaming adhesives. Further, current adhesives do notprovide sufficient bonding strength at the seam, resulting in short beltlife. In addition, the seam must have the appropriate surface propertiesin order to allow for sufficient toner release at the seam.

[0010] Currently, puzzle cut seam adhesives consist of insulatingultraviolet-curable epoxies and hot-melt adhesives. While theseadhesives exhibit acceptable strengths at room temperature under tensileload, most undergo premature failure at elevated temperatures.Additionally, the existing adhesives have been found to perform poorlyunder some important dynamic test conditions.

[0011] Therefore, it is desired to provide a more robust adhesive systemuseful to seam puzzle cut seamed belts. It is further desirable toprovide an adhesive system that allows the seam to have thermal andmechanical characteristics closely matching those of the robustsubstrate. Further, it is desired to provide an adhesive havingelectrical, mechanical and toner release characteristics that closelymatch those of the substrates. In addition, it is desirable to provide aseam which is imageable, thereby reducing or eliminating the presence ofprint or copy defects.

[0012] U.S. Pat. No. 5,549,193 relates to an endless flexible seamedbelt comprising puzzle cut members, wherein at least one receptacle hasa substantial depth in a portion of the belt material at the belt ends.

[0013] U.S. Pat. No. 5,721,032 discloses a puzzle cut seamed belt havinga strength-enhancing strip.

[0014] U.S. Pat. No. 5,487,707 discloses a puzzle cut seamed belt havinga bond between adjacent surfaces, wherein an ultraviolet cured adhesiveis used to bond the adjacent surfaces.

[0015] U.S. Pat. No. 5,514,436 relates to a puzzle cut seamed belthaving a mechanically invisible seam, which is substantially equivalentin performance to a seamless belt.

SUMMARY OF THE INVENTION

[0016] Embodiments of the present invention include: an endless seamedflexible belt comprising a first end and a second end, each of the firstend and the second end comprising a plurality of mutually matingelements which join in an interlocking relationship to form a seam, thebelt comprising a substrate and the seam comprising an adhesivecomprising a resistive, hot-melt processible, thermosetting resin and acarbon filler.

[0017] In addition, embodiments of the present invention include: anendless seamed flexible belt comprising a first end and a second end,each of the first end and the second end comprising a plurality ofmutually mating elements which join in an interlocking relationship toform a seam, the belt comprising a polyimide substrate, and the seamcomprising an adhesive comprising a carbon filler and a resistive,hot-melt processable, thermosetting resin polymer selected from thegroup consisting of polyvinyl butyral, nitrile phenolic resin, epoxyphenolic resin, and mixtures thereof.

[0018] Embodiments further include: an image forming apparatus forforming images on a recording medium comprising: a charge-retentivesurface to receive an electrostatic latent image thereon; a developmentcomponent to apply toner to the charge-retentive surface to develop theelectrostatic latent image to form a developed image on the chargeretentive surface; a transfer belt to transfer the developed image fromthe charge retentive surface to a copy substrate, wherein the transferbelt is an endless seamed flexible belt comprising a first end and asecond end, each of the first end and the second end comprising aplurality of mutually mating elements which join in an interlockingrelationship to form a seam, the transfer belt comprising a substrateand the seam comprising an adhesive comprising a resistive, hot-meltprocessible, thermosetting resin and a fluorinated carbon filler, and afixing component to fuse the developed image to the copy substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a better understanding of the present invention, referencemay be had to the accompanying figures.

[0020]FIG. 1 is a depiction of an electrostatographic apparatus.

[0021]FIG. 2 is an enlargement of a transfer system according to anembodiment of the present invention.

[0022]FIG. 3 is an enhanced view of an embodiment of a beltconfiguration and seam according to the present invention.

[0023]FIG. 4 is an enlargement of a puzzle cut seam having a head andneck members according to one embodiment of the present invention.

[0024]FIG. 5 is an enlargement of a puzzle cut seam havingmushroom-shaped puzzle cut members according to another embodiment ofthe present invention.

[0025]FIG. 6 is an enlargement of a puzzle cut seam having dovetailmembers according to another embodiment of the present invention.

[0026]FIG. 7 is an enlargement of a puzzle cut seam having recessor andteeth members according to another embodiment of the present invention.

[0027]FIG. 8 is an enlargement of a puzzle cut seam having receptacleand projection members of differing depth according to anotherembodiment of the present invention.

[0028]FIG. 9 is an enlarged version of a belt according to oneembodiment of the present invention and demonstrates a crevice betweenthe puzzle cut members, the crevice containing an adhesive.

[0029]FIG. 10 is an enlarged cross-sectional view of a belt according toa preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0030] The present invention relates to an endless flexible seamed belthaving a puzzle cut seam, wherein the seam comprises an adhesivecomprising a polymer and at least one electrically conductive filler. Inpreferred embodiments, the polymer is a resistive, hot-melt processible,thermosetting resin. The adhesive provides a seam, in embodiments, whichis imageable and wherein the occurrence of copy and print defects at theseam is reduced or eliminated. Image transfer is accomplished partlybecause the present seam possesses the desired conductivity and releaseproperties required for sufficient transfer. Image transfer is furthermade possible because the adhesive seam of the present invention isvirtually or completely free of bubbles, voids, and other inclusionswhich may impact high quality image transfer at the seam region. Thepresent invention further provides, in embodiments, a belt wherein theseam and belt material share electrical, mechanical and toner releasecharacteristics. The present invention further provides, in embodiments,a belt having virtual uniform thickness at the seam. The presentinvention, in embodiments, provides a seamed belt having enhancedbonding strength at the seam because the adhesive is crosslinked.Moreover, the present invention, in embodiments provides a seam with anadhesive that is inert towards, and thereby unaffected by, most if notall oils, lubricants, releasing agents or toner additives to which thebelt seam may be exposed.

[0031] In preferred embodiments, the belt is an intermediate transferbelt, sheet, roller, or film useful in xerographic, including digital,apparatuses. However, the belts herein having a seam comprising acontrolled conductivity, hot-melt processable, thermosetting adhesive,can be useful as belts, rollers, drelts, and the like, for manydifferent processes and components such as photoreceptors, fusingmembers, transfix members, bias transfer members, bias charging members,developer members, image bearing members, conveyor members, cleaningmembers, and other members for contact electrostatic printingapplications, xerographic applications, including digital, and the like.Further, the belts, herein, can be used for both liquid and dry powderxerographic architectures.

[0032] Referring to FIG. 1, in a typical electrostatographic reproducingapparatus, a light image of an original to be copied is recorded in theform of an electrostatic latent image upon a photosensitive member andthe latent image is subsequently rendered visible by the application ofelectroscopic thermoplastic resin particles which are commonly referredto as toner. Specifically, photoreceptor 10 is charged on its surface bymeans of a charger 12 to which a voltage has been supplied from powersupply 11. The photoreceptor is then imagewise exposed to light from anoptical system or an image input apparatus 13, such as a laser and lightemitting diode, to form an electrostatic latent image thereon.Generally, the electrostatic latent image is developed by bringing adeveloper mixture from developer station 14 into contact therewith.Development can be effected by use of a magnetic brush, powder cloud, orother known development process.

[0033] After the toner particles have been deposited on thephotoconductive surface, in image configuration, they are transferred toa copy sheet 16 by transfer means 15, which can be pressure transfer orelectrostatic transfer. Preferably, the developed image can betransferred to an intermediate transfer member and subsequentlytransferred to a copy sheet.

[0034] After the transfer of the developed image is completed, copysheet 16 advances to fusing station 19, depicted in FIG. 1 as fusing andpressure rolls, wherein the developed image is fused to copy sheet 16 bypassing copy sheet 16 between the fusing member 20 and pressure member21, thereby forming a permanent image. Fusing may be accomplished byother fusing members such as a fusing belt in pressure contact with apressure roller, fusing roller in contact with a pressure belt, or otherlike systems. Photoreceptor 10, subsequent to transfer, advances tocleaning station 17, wherein any toner left on photoreceptor 10 iscleaned therefrom by use of a blade 22 (as shown in FIG. 1), brush, orother cleaning apparatus.

[0035]FIG. 2 is a schematic view of an image development systemcontaining an intermediate transfer member. FIG. 2 demonstrates anotherembodiment of the present invention and depicts a transfer apparatus 15comprising a transfer member 2 positioned between an imaging member 10and a transfer roller 6. The imaging member 10 is exemplified by aphotoreceptor drum. However, other appropriate imaging members mayinclude other electrostatographic imaging receptors such as ionographicbelts and drums, electrophotographic belts, and the like.

[0036] In the multi-imaging system of FIG. 2, each image beingtransferred is formed on the imaging drum by image forming station 12.Each of these images is then developed at developing station 13 andtransferred to transfer member 2. Each of the images may be formed onthe photoreceptor drum 10 and developed sequentially and thentransferred to the transfer member 2. In an alternative method, eachimage may be formed on the photoreceptor drum 10, developed, andtransferred in registration to the transfer member 2. In a preferredembodiment of the invention, the multi-image system is a color copyingsystem. In this color copying system, each color of an image beingcopied is formed on the photoreceptor drum. Each color image isdeveloped and transferred to the transfer member 2. As above, each ofthe colored images may be formed on the drum 10 and developedsequentially and then transferred to the transfer member 2. In thealternative method, each color of an image may be formed on thephotoreceptor drum 10, developed, and transferred in registration to thetransfer member 2.

[0037] After latent image forming station 12 has formed the latent imageon the photoreceptor drum 10 and the latent image of the photoreceptorhas been developed at developing station 13, the charged toner particles4 from the developing station 13 are attracted and held by thephotoreceptor drum 10 because the photoreceptor drum 10 possesses acharge 5 opposite to that of the toner particles 4. In FIG. 2, the tonerparticles are shown as negatively charged and the photoreceptor drum 10is shown as positively charged. These charges can be reversed, dependingon the nature of the toner and the machinery being used. In a preferredembodiment, the toner is present in a liquid developer. However, thepresent invention, in embodiments, is also useful for dry developmentsystems.

[0038] A biased transfer roller 6 positioned opposite the photoreceptordrum 10 has a higher voltage than the surface of the photoreceptor drum10. As shown in FIG. 2, biased transfer roller 6 contact charges thebackside 7 of transfer member 2 with a positive charge. In analternative embodiment of the invention, a corona or any other chargingmechanism may be used to charge the backside 7 of the transfer member 2.

[0039] The negatively charged toner particles 4 are attracted to thefront side 8 of the transfer member 2 by the positive charge 9 on thebackside 7 of the transfer member 2.

[0040]FIG. 3 demonstrates an example of an embodiment of a belt inaccordance with the present invention. Belt 30 is demonstrated with seam31. Seam 31 is pictured as an example of one embodiment of a puzzle cutseam. The belt is held in position and turned by use of rollers 32. Notethat the mechanical interlocking relationship of the seam 31 is presentin a two-dimensional plane when the belt 30 is on a flat surface,whether it be horizontal or vertical. While the seam is illustrated inFIG. 3 as being perpendicular to the two parallel sides of the belt, itshould be understood that it may be angled or slanted with respect tothe parallel sides. This enables any noise generated in the system to bedistributed more uniformly and the forces placed on each mating elementor node to be reduced.

[0041] The seam formed according to the present invention is one havinga thin and smooth profile, of enhanced strength, improved flexibilityand extended mechanical life. In a preferred embodiment, the belt endsare held together by the geometric relationship between the ends of thebelt material, which are fastened together by a puzzle cut. The puzzlecut seam can be of many different configurations, but is one in whichthe two ends of the seam interlock with one another in a manner of apuzzle. Specifically, the mutually mating elements comprise a firstprojection and a second receptacle geometrically oriented so that thesecond receptacle on the first end receives the first projection on thesecond end and wherein the first projection on the first end is receivedby the second receptacle on the second end. The seam has a kerf, void orcrevice between the mutually mating elements at the two joining ends ofthe belt, and that crevice can be filled with an adhesive according tothe present invention. The opposite surfaces of the puzzle cut patternare bound or joined together to enable the seamed flexible belt toessentially function as an endless belt. In the present invention, theseam including the puzzle cut members, is held together by a resistive(controlled conductivity), hot-melt processable, thermosetting adhesive,which is compatible with the rest of the belt. The belt, in embodiments,provides improved seam quality and smoothness with substantially nothickness differential between the seam and the adjacent portions of thebelt.

[0042] An example of an embodiment of a puzzle cut seam having two ends,each of the ends comprising puzzle cut members or mutually matingelements is shown in FIG. 4. The puzzle cut pattern may take virtuallyany form, including that of nodes such as identical post or neck 34 andhead 33 or node patterns having projections 36 and receptacles 35 whichinterlock when brought together as illustrated in FIG. 4. The puzzle cutpattern may also be of a more mushroom-like shaped pattern having firstprojections 38 and 39 and second receptacles 40 and 37 as illustrated inFIG. 5, as well as a dovetail pattern as illustrated in FIG. 5 havingfirst projections 41 and second receptacles 42. The puzzle cut patternillustrated in FIG. 7 has a plurality of first fingers 43 withinterlocking teeth 44 and plurality of second fingers 45 which haverecesses 46 to interlock with the teeth 44 when assembled. It ispreferred that the interlocking elements all have curved mating elementsto reduce the stress concentration between the interlocking elements andpermit them to separate when traveling around curved members such as therolls 32 of FIG. 3. It has been found that with curved mating elementsthat the stress concentration is lower than with square corners whererather than the stress being uniformly distributed it is concentratedleading to possible failure.

[0043] Another example of a puzzle cut seam is shown in FIG. 8 in whichthe mutually mating elements or puzzle cut members comprise a firstmember 50 and a second member 51, wherein the first member 50 comprisesa first receptacle 52 and a first projection 54, and the second member51 comprises a second receptacle 55 and a second projection 56. Thefirst receptacle 52 of the first member 50 receives the secondprojection 56 of the second member 51, and the second receptacle 55 ofthe second member 51 receives the first projection 54 of the firstmember 50. In order to reduce the height differential between the seamedportion and the adjacent, unseamed portion of the belt, it is desirableto have the second receptacles formed within their individual members ata substantial depth in a portion of the belt at the belt ends.

[0044] The height differential between the seam and the rest of the belt(the nonseamed portions of the belt) can be practically nil, or fromabout −25 to about +50 micrometers, preferably from about −5 to about +5micrometers, and particularly preferred of from about −1 to about +1micrometers.

[0045] A resistive, hot-melt processible, thermosetting adhesive ispreferably present between the seam, and placed in the crevice betweenthe puzzle cut members to a thickness of from about 0.0001 to about 50micrometers. As shown in one embodiment of a puzzle cut seam 31according to the present invention, the adhesive is present between thepuzzle cut members and at the seam crevice 57 of FIG. 9.

[0046] The adhesive is preferably chosen to have a resistivity withinthe range desired for electrostatic transfer of toner. Preferably, theresistivity of the seam is the same or similar to that of the belt inorder to provide the same electrical properties for the seam and therest of the belt. A preferred volume resistivity for toner transferperformance is from about 10¹ to about 10¹³ ohm-cm, and preferably fromabout 10⁸ to about 10¹¹ ohm-cm. This is the preferred volume resistivityfor the seam and the rest of the belt. It is preferred that the adhesivemake good electrical contact with the belt material. When the belt andthe seam of the belt have a same or substantially the same electricalresistance, the toner transfer at the seam is the same or substantiallythe same as the transfer at the belt. Such transfer at the seam providesan invisible or substantially invisible seam.

[0047] The electrical properties can be tailored by varying the amountof fillers, by changing the type of filler added, and/or by changing thecuring procedure.

[0048] A preferred adhesive for use with a belt seam, preferably apuzzle cut belt seam, is a resistive, hot-melt processible,thermosetting composite. By “resistive,” Applicants refer to an adhesivecomposite with electrical resistivity failing in the range of from about10⁶ to about 10¹³ ohm-cm. By the term “hot-melt processible,” Applicantsare referring to a resin which will melt and flow under conditions ofapplied heat and pressure. By the term “thermosetting resin,” Applicantsare referring to a resin which upon sufficient applied heating, willundergo a chemical reaction, for example crosslinking, that causes apermanent change of state of the resin to an insoluble, intractable andthermally stable form.

[0049] Preferred resistive, hot-melt processable, thermosetting adhesiveresins include polyvinyl butyral, phenolic resins, and mixtures thereof.Preferred phenolic resins include nitrile phenolic resins (for example,nitrile phenolic acrylic resins), epoxy phenolic resins, and the like,polymers thereof and mixtures thereof. Particularly preferred adhesiveresins include polyvinyl butyral resins, nitrile phenolic resins, andmixtures thereof. Commercially available resins for adhesives includepolyvinyl butyral resins such as PLYMASTER® 2130 from Norwood CoatedProducts and Butvars® from Monsanto; nitrile phenolic acrylic resinssuch as MODAR® 816, 824HT and the like from Ashland Chemicals,nitrile-phenolic rubber such as PLYMASTER® HT4033, PM216 and the likefrom Norwood Coated Products, and the like.

[0050] A suitable, fine powder, conductivity-enhancing filler that isuniformly dispersed without agglomerates in the above resins, ispreferably used with the present adhesive. The filler can be a carbonfiller, metal or metal oxide filler, doped metal oxide filler,conductive polymer filler, or other conductive filler or blends thereof.Preferably, the filler is a carbon filler such as carbon black,graphite, or the like, and more preferably is a fluorinated carbonfiller. Preferred fluorinated carbons include those having the formulaCF_(x) with x representing the number of fluorine atoms and generallybeing up to about 1.5, preferably from about 0.01 to about 1.5, andparticularly preferred from about 0.04 to about 1.4. Other preferredfluorinated carbons are poly(dicarbon monofluoride) which is usuallywritten in the shorthand manner (C₂F)_(n). Preferred fluorinated carbonsselected include those described in U.S. Pat. No. 4,524,119 to Luly etal., the subject matter of which is hereby incorporated by reference inits entirety, and those having the tradename ACCUFLUOR®. ACCUFLUOR® isproduced by Advance Research Chemicals, Inc., Catoosa Okla. Examplesinclude ACCUFLUOR® 2028, ACCUFLUOR® 2065, ACCUFLUOR® 1000, andACCUFLUOR® 2010. ACCUFLUOR® 2028 and ACCUFLUOR® 2010 have 28 and 11percent by weight fluorine, respectively, based on the weight offluorinated carbon. ACCUFLUOR® 1000 and ACCUFLUOR® 2065 have 62 and 65percent by weight fluorine, respectively, based on the weight offluorinated carbon. Also, ACCUFLUOR® 1000 comprises carbon coke, whereasACCUFLUOR® 2065, 2028 and 2010 all comprise conductive carbon black.These fluorinated carbons are of the formula CF_(x) and are formed bythe reaction of C+F₂=CF_(x).

[0051] Preferably, the filler is present in the adhesive in an amount offrom about 1 to about 40, and preferably from about 4 to about 10percent by weight of total solids. Total solids, as used herein, refersto the amount of filler, optional compatibilizer, other possibleadditives, resin and other solids present in the adhesive.

[0052] The adhesive in solution may be applied at the seam and betweeninterlocking seaming members, by any suitable means including liquidmeans such as using a cotton-tipped applicator, liquid dispenser, gluegun or the like, or by dry processes such as by using a dry tape. Anamount of adhesive sufficient to fill the seam when dry is added betweeninterlocking seaming members.

[0053] In general, the process for seaming using the adhesive hereininvolves compounding in a suitable solvent, such as a blend of ethanoland methylethylketone, the resin with the filler, followed by drying ofthe liquid-phase composite into a solid phase, thin layer, adhesivefilm. The use of a compatibilizer additive is preferred to reliablyachieve the desired electrical properties at minimal loading of theconductive filler.

[0054] More specifically, the process entails compounding either in themelt phase below the critical temperature where crosslinking occurs, orin a suitable solution with a conductive filler or other suitableconductivity enhancing filler. This is followed by forming theliquid-phase composite into a solid phase, thin layer, adhesive film bymeans of blade-coating, spray-coating, or extruding the liquid phaseonto a release backing. Preferably a low temperature drying procedure(for example, from about 30 to about 50° C.) is employed to removesolvents and dry the liquid-phase adhesive. A post cure step can be partof the seaming process, after the adhesive has been melted and flowedinto the seam.

[0055] The adhesive film composite, with or without a removable releasebacking, is then applied to align with only the puzzle-interlockedseamed region of the belt or film member. The seam is then pressedbetween parallel heated plates, for example the jaws of a Vertrod seamwelder. The seam can then be cured by various methods. Curing proceduresuseful in curing the seam include thermal curing and infrared curing.Examples of heat curing include use of moderate to high heat once theadhesive is placed in the seam crevice. This heating also induces thecrosslinking/solidification reaction and increases the seam processingand belt fabrication speed. Desired temperature includes from about 40to about 250° C., preferably from about 100 to about 150° C., at a timeof from about 30 seconds to about 24 hours, preferably from about 5minutes to about 2 hours, and particularly preferred, from about 5minutes to about 15 minutes. The pressure during the heat curing is fromabout 0.5 psi to about 100 psi, and particularly preferred from about 2psi to about 60 psi. Increased pressure enables welding at lowertemperatures and vise versa. Heat may be applied by, for example, awelder, heat gun, oven, or other suitable means.

[0056] It is preferred in some cases that a second post-cure is carriedout in order to sufficiently crosslink the lower molecular weightoligomers into a higher molecular weight polymeric network. Preferably,the second post cure occurs at a higher temperature than the first cure.The temperature of the second cure is from about 120 to 200° C. at atime of from about 30 seconds to about 24 hours and more preferably 20minutes to about 1 hour, and at a pressure of from about 0.5 psi toabout 100 psi and particularly preferred from about 2 psi to about 10psi.

[0057] By applying the adhesive to the seam and forming the virtual seamas indicated, a cost savings of at least 5 times the cost of a coatedseam results.

[0058] The substrate must be robust to undergo multiple cycling throughrigorous use. Examples of suitable substrate materials includesemiconductive polyimides such as polyanaline polyimide, carbon filledpolyimides, carbon filled polycarbonate, carbon filled polyesters, andthe like. Examples of commercially available polyimide substratesinclude KAPTON® and UPLIEX® both from DuPont, and ULTEM from GE. Exampleof commercially available polyesters include Mylar® from Dupont, and thelike.

[0059] The substrate may include a filler. Preferably, the filler, ifpresent in the substrate, is present in an amount of from about 1 toabout 60, and preferably from about 3 to about 40 percent by weight oftotal solids. Examples of suitable fillers for use in the substrateinclude carbon fillers, metal oxide fillers, doped metal oxide fillers,other metal fillers, polymer fillers, other conductive fillers, and thelike. Specific examples of fillers include carbon fillers such as carbonblack, fluorinated carbon black, graphite, low conductive carbon, andthe like, and mixtures thereof; metal oxides such as indium tin oxide,zinc oxide, iron oxide, aluminum oxide, copper oxide, lead oxide, andthe like, and mixtures thereof; doped metal oxides such asantimony-doped tin oxide, antimony-doped titanium dioxide,aluminum-doped zinc oxide, similar doped metal oxides, and mixturesthereof; and polymer particles such as polytetrafluoroethylene,polypyrrole, polyanaline, doped polyanaline, polythiophene and the like,and mixtures thereof. Preferred fillers include carbon black, antimonydoped tin oxide, doped polyanaline, and mixtures thereof.

[0060] In an optional embodiment of the invention, an overcoat is coatedon the substrate following seaming with the resistive, hot-meltprocessable, thermosetting adhesive. Preferred overcoats includefluoropolymers, silicones, vinyl butyral composites, and the likeovercoats.

[0061] In the preferred embodiment wherein a coating is applied to thesubstrate following seaming, it is preferred to add a filler to thecoating. Examples of suitable fillers include the fillers listed aboveas suitable for use in the resistive, hot-melt processable,thermosetting adhesive and include carbon fillers, metal oxide fillers,doped metal oxide fillers, other conductive filers, and the like. Otherfillers may be used, such as fillers having a purpose of altering thesurface and mechanical properties. These include polytetrafluoroethylenepowder, and the like. A particularly preferred filler is fluorinatedcarbon such as ACCUFLUOR®, as described above.

[0062] An example of a preferred belt used in combination with theresistive, hotmelt processable, thermosetting resin adhesive is depictedin FIG. 10. The belt 30 comprises a substrate 60, having therein, inpreferred embodiments, conductive fillers 61. The belt contains seam 31having an adhesive 63 positioned between the seam members 64 and 65. Ina preferred embodiment, conductive fillers 62 are dispersed or containedin the adhesive. In an optional embodiment of the invention, an overcoat66 is provided in the substrate 60. The overcoat may contain conductivefillers 67. Conductive fillers 61 optionally dispersed or contained onthe substrate, fillers 67 optionally dispersed or contained in theoptional overcoat, and fillers 62 optionally contained or dispersed inthe adhesive, may be the same or different.

[0063] The adhesive herein provides an excellent seam adhesive forbelts, and in preferred embodiments, polyimide intermediate transferbelts. Using a two-stage cure procedure, a fully-filled, void-free, highquality seam interface enabling image-on-seam performance can beprepared. The adhesive, in embodiments, has the same or similarmechanical and surface release properties as the substrate. Further, theadhesive, in embodiments, provides good bonding strength to thesubstrate seam members. The resistivity of the adhesive can be tunedinto the same range as the substrate by changing the loading level ofthe conductive filler, by mixing different ratios of the conductivefillers, or by varying curing conditions.

[0064] All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

[0065] The following Examples further define and describe embodiments ofthe present invention. Unless otherwise indicated, all parts andpercentages are by weight.

EXAMPLES Example 1

[0066] Preparation of Intermediate Transfer Belt

[0067] A polyimide film substrate was obtained from DuPont. The beltsubstrate comprised polyaniline and carbon filled polyimide. Theresistivity was tested and found to be from about 10⁹ to about 10¹⁰ohm-cm. The belt ends that were to be joined were subjected to a“chemical etch” treatment to help improve adhesion. The puzzle cut endswere dipped in 1N aqueous NaOH solution for about 10 minutes, followedby 10 minutes in 1N aqueous HCl solution. The ends were rinsed withdistilled water and allowed to dry.

Example 2

[0068] Preparation of Polyvinyl Butyral and Fluorinated Carbon Adhesive

[0069] A stock solution of polyvinyl butyral (PVB) adhesive was preparedby dissolving 62 grams of polyvinyl butyral (Norwood PLYMASTER® 2130)adhesive film in a mixture of 200 g ethyl alcohol, and 100 grams 1-butylalcohol in a 500 ml glass bottle. The mixture was allowed to mix on aroll mill overnight. Into a 4 ounce glass bottle was added 15 grams ofMEK, 0.128 grams of ACCUFLUOR® 2028 and 0.0425 g ACCUFLUOR® 2010(fluorinated carbons from Advance Research Chemicals, Inc., Catoosa,Okla.). The carbons were then dispersed in the solvent by mixing andplacing the bottle in an ultrasonic bath for about 10 to 15 minutes. Tothe bottle was then added 0.17 g DIAK3® (Dupont) and mixed well. About25 grams of the PVB stock solution was added and the dispersion wasmixed on a roll mill for about 1 hour.

[0070] The resulting dispersion was drawcoated onto a sheet of releasingfilm. Alternatively, a piece of plate glass can be used. A suitablesized coating bar was used. The coating was allowed to dry in a dryingoven set at about 40° C. Once the film was dry, it was peeled off therelease paper and was ready for use as a seam adhesive.

[0071] At this stage, the film did not exhibit any controlledconductivity. In fact, conductivity was only achieved when the film wassubjected to a second thermal postcure step. A 0.001 inch thick sampleadhesive film coated on stainless steel substrate and postcured at about150° C. for about 30 minutes was observed to have a resistivity of about2×10⁹ ohm-cm. This formulation was repeated and the electrical resultswere found to be reproducible. It was also found that temperature andhumidity changes did not affect the electrical properties of theadhesive material. The resistivity was tuned by adjusting the amountand/or type of fluorinated carbon, curatives, and postcure parameters.

Example 3

[0072] Preparation of Polyvinyl Butyral and Fluorinated Carbon AdhesiveA solution of polyvinyl butyral (PVB) adhesive was prepared bydissolving 31 grams of polyvinyl butyral (Norwood PLYMASTER® 2130)adhesive film in a mixture of 100 grams ethyl alcohol, 50 grams 1-butylalcohol, 10 grams methyl alcohol and 1 gram of fluorosurfactant (FC-430from 3M) in a 500 ml. glass bottle. The mixture was allowed to mix on aroll mill overnight. Into an 8 ounce bottle was added 85 grams of methylethyl ketone and 2.47 grams of fluorinated carbon (ACCUFLUOR® 2028 fromAdvance Research Chemicals, Inc., Catoosa, Okla.). The fluorinatedcarbon was dispersed in the solvent by vigorous mixing and then placingthe bottle in an ultrasonic bath for about 10 to 15 minutes. About 1.24grams of Dupont DIAK 3 was added to the carbon dispersion. Thisdispersion was then placed on the roll mill for about 15 minutes. Thiscarbon dispersion was transferred to the bottle of PVB stock solutionand the resulting mixture was mixed on a roll mill for about 1 hour. Theresulting dispersion was drawcoated onto a sheet of releasing film.Alternatively, a piece of plate glass can be used. A suitable sizedcoating bar was used. The coating was allowed to dry in a drying ovenset at about 40° C. Once the film was dry, it was peeled off the releasepaper and was ready for use as a seam adhesive.

[0073] At this stage, the film did not exhibit any controlledconductivity. As with the adhesive prepared in Example 2, conductivitywas only achieved when the film was subjected to a thermal postcurestep. A 0.001 inch thick sample film coated on stainless steel substrateand postcured at about 150° C. for about 30 minutes was observed to havea resistivity of about 2×10⁹ ohm-cm. This formulation was repeated andthe electrical results were found to be reproducible. It was also foundthat temperature and humidity changes did not affect the electricalproperties of the adhesive material. The resistivity was tuned byadjusting the amount and/or type of fluorinated carbon, curatives,compatibilizer and postcure parameters.

Example 4

[0074] Preparation of Image-on-Seam Puzzle Cut Seamed Belt

[0075] The two puzzle cut ends of the polyimide film prepared in Example1 were brought together and aligned on the lower jaw of a modifiedTechnoseal Vertrod Thermal Impulse Heat Sealer (Mod.20EP/P-1/4-WC-CAN-DIG-I) with the assistance of vacuum holdown tablesmounted on both sides of a welder. A freestanding film of the adhesives(preferably about 15-125 microns thick) formed in accordance withExamples 2 or 3 were selected. A narrow strip (about {fraction (3/16)}inch wide) of material was cut to a length and width sufficient toadequately cover the puzzle-cut seam area on the belt substrate. Thestrip of tape was laid across the top of the seam area covering the seamThe welder was “programmed” to weld at an initial temperature of about235° F. for 3 minutes then ramped to about 320° F. for an additional 30minutes. The two step welding was performed as a continuous process inthe welder. This caused the adhesive film to melt and flow into the seamarea filling it completely, followed by crosslinking of the adhesive andactivation of the conductivity. Alternately, the belt can be mounted ina clamping fixture and the seam area can be pressed between parallelsmooth surfaces to immobilize the seam area during a thermal postcurestep of 150° C. for 30 minutes in an oven.

[0076] The seamed belt was removed from the fixture and the seam wassubjected to finishing (sanding) and polishing steps to remove excessadhesive and bring the seam area topography in line with the rest of thebelt.

[0077] While the invention has been described in detail with referenceto specific and preferred embodiments, it will be appreciated thatvarious modifications and variations will be apparent to the artisan.All such modifications and embodiments as may readily occur to oneskilled in the art are intended to be within the scope of the appendedclaims.

We claim:
 1. An endless seamed flexible belt comprising a first end anda second end, each of the first end and the second end comprising aplurality of mutually mating elements which join in an interlockingrelationship to form a seam, the belt comprising a substrate and theseam comprising an adhesive comprising a resistive, hot-meltprocessible, thermosetting resin and a carbon filler.
 2. An endlessseamed flexible belt in accordance with claim 1, wherein said carbonfiller is a fluorinated carbon filler.
 3. An endless seamed flexiblebelt in accordance with claim 2, wherein said fluorinated carbon has theformula CF_(x), wherein x is a number of from about 0.01 to about 1.5.4. An endless seamed flexible belt in accordance with claim 3, wherein xis a number of from about 0.04 to about 1.4.
 5. An endless seamedflexible belt in accordance with claim 2, wherein said fluorinatedcarbon is selected from the group consisting of fluorinated carbonhaving about 28 percent by weight fluorine, a fluorinated carbon havingabout 11 percent by weight fluorine, a fluorinated carbon having about62 percent by weight fluorine, and a fluorinated carbon having about 65percent by weight fluorine, based on the weight of fluorinated carbon.6. An endless seamed flexible belt in accordance with claim 1, whereinsaid resistive, hot-melt processible, thermosetting resin is selectedfrom the group consisting of polyvinyl butyral resin, phenolic resin,and mixtures thereof.
 7. An endless seamed flexible belt in accordancewith claim 6, wherein said phenolic resin is selected from the groupconsisting of nitrile phenolic, epoxy phenolic, and mixtures thereof. 8.An endless seamed flexible belt in accordance with claim 6, wherein saidresistive, hot-melt processible, thermosetting resin comprises polyvinylbutyral and phenolic resins.
 9. An endless seamed flexible belt inaccordance with claim 6, wherein said resistive, hot-melt processible,thermosetting resin is nitrile phenolic acrylic resin.
 10. An endlessseamed flexible belt in accordance with claim 1, wherein said adhesiveis crosslinked.
 11. An endless seamed flexible belt in accordance withclaim 1, wherein said substrate comprises a polymer selected from thegroup consisting of polyimide, polyester, and polycarbonate.
 12. Anendless seamed flexible belt in accordance with claim 11, wherein saidpolyimide is a polyanaline polyimide.
 13. An endless seamed flexiblebelt in accordance with claim 1, wherein said substrate comprises aconductive filler.
 14. An endless seamed flexible belt in accordancewith claim 13, wherein said filler is selected from the group consistingof carbon fillers, doped metal oxide fillers, polymer fillers, andmixtures thereof.
 15. An endless seamed flexible belt in accordance withclaim 14, wherein said carbon filler is selected from the groupconsisting of carbon black, graphite, and fluorinated carbon.
 16. Anendless seamed flexible belt in accordance with claim 14, wherein saiddoped metal oxide is antimony doped tin oxide.
 17. An endless seamedflexible belt in accordance with claim 14, wherein said polymer fillersare selected from the group consisting of polytetrafluoroethylene,polypyrrole, and polyanaline.
 18. An endless seamed flexible belt inaccordance with claim 13, wherein said conductive filler comprisespolyanaline and carbon black.
 19. An endless seamed flexible belt inaccordance with claim 1, wherein said seam has a volume resistivity offrom about 10¹ to about 10¹³ ohm-cm.
 20. An endless seamed flexible beltin accordance with claim 19, wherein said seam has a volume resistivityof from about 10⁸ to about 10¹¹ ohm-cm.
 21. An endless seamed flexiblebelt in accordance with claim 1, wherein said substrate comprises anovercoat thereon.
 22. An endless seamed flexible belt in accordance withclaim 1, wherein said belt is an intermediate transfer belt.
 23. Anendless seamed flexible belt in accordance with claim 1, wherein saidplurality of mutually mating elements are in the form of a puzzle cutpattern.
 24. An endless seamed flexible belt in accordance with claim23, wherein said mutually mating elements comprise a first projectionand a second receptacle geometrically oriented so that said secondreceptacle on the first end receives the first projection on the secondend and wherein said first projection on said first end is received bysaid second receptacle on the second end to form a joint between thefirst and second ends.
 25. An endless seamed flexible belt in accordancewith claim 24, wherein said first projection and said second receptacleare curved.
 26. An endless seamed flexible belt comprising a first endand a second end, each of the first end and the second end comprising aplurality of mutually mating elements which join in an interlockingrelationship to form a seam, said belt comprising a polyimide substrate,and the seam comprising an adhesive comprising a carbon filler and aresistive, hot-melt processible, thermosetting resin polymer selectedfrom the group consisting of polyvinyl butyral, nitrile phenolic resin,epoxy phenolic resin, and mixtures thereof.
 27. An image formingapparatus for forming images on a recording medium comprising: acharge-retentive surface to receive an electrostatic latent imagethereon; a development component to apply toner to the charge-retentivesurface to develop the electrostatic latent image to form a developedimage on said charge retentive surface; a transfer belt to transfer thedeveloped image from the charge retentive surface to a copy substrate,wherein the transfer belt is an endless seamed flexible belt comprisinga first end and a second end, each of the first end and the second endcomprising a plurality of mutually mating elements which join in aninterlocking relationship to form a seam, the transfer belt comprising asubstrate and the seam comprising an adhesive comprising a resistive,hot-melt processible, thermosetting resin and a fluorinated carbonfiller, and a fixing component to fuse the developed image to the copysubstrate.